Effect of Reducing Thickness of TiN Buffer Layers on Epitaxial Growth of GaN Layes
We investigated effect of reducing thickness of TiN buffer layers on growth of the smooth GaN layers. The sputtered TiN layers with thicknesses in the range of 2 to 100 nm were deposited on sapphire substrates. The sputtered TiN layers were exposed NH3 + H2 mixed gas atmosphere at about 1000°C to enrich nitrogen concentration of the layers. GaN layers were deposited on the nitrogen-enriched TiN layer using a MOCVD method. Average grain size of the nitrogen-enriched TiN layer was minimized at the thickness of 5 nm. In the initial stages of GaN growth, density of GaN hexagons grown on the 5nm-thick TiN layers was the highest. The 2μm-thick GaN layers grown on the 5nm-thick TiN layers exhibited the smoothest surface. Thus, the 5nm thickness is believed to be the best thickness for the smooth GaN growth on the sapphire/TiN substrates.
Young Won Chang, Nack J. Kim and Chong Soo Lee
K. Ito et al., "Effect of Reducing Thickness of TiN Buffer Layers on Epitaxial Growth of GaN Layes", Materials Science Forum, Vols. 561-565, pp. 1217-1220, 2007